lwong82d:

Just because a person has a problem with self-esteem around a particular person doesn't mean they have to be the only one to fix it or deal with it.

Actually, they do. Self-esteem is an internal quantity. No one else can fix it.

lwong82d:

The older sister should step up and tell her little sister that unless that specific area of medicine is absolutely the direction she must go, choose a different path.

I think this would be extremely silly. "I've called being a doctor first!" It will be a long time before her sister can be a doctor of anything. She'd have to take her prerecs, study for the MCAT, pass it, get into medical school, get through medical school, and intern before she'd be heading out into the "real" world. She may find a different speciality. She may realize that she's a little bit on the old side for such a drastic career change. I think the LW is worrying about something that may never happen, and it's something that the LW should deal with.

lwong82d:

She is completely right in her concern of her sister overshadowing her. Her colleagues will be comparing the two; and yes, so will patients.

The patients? Well, maybe if they work at the same practice but that's pretty doubtful. As for her colleagues, that really depends. It doesn't sound like the LW is a bigshot in the medical community, and her sister will be far too old to be one, so they'll compare roughly the same.

lwong82d:

Let her know that you have your own life and are quite happy with it. Tell her she will never find happiness pursuing someone else's life and to get her own.

I think the LW should worry about her own happiness before instructing others. She claims to be close to her sister. Did she ever stop to think that her sister may find her descriptions of her job compelling, or that maybe she looks up to her big sister and wants to be like her?